Patch Bag Having Separated Tear Initiators

ABSTRACT

A patch bag has a heat-shrinkable patch adhered to a heat-shrinkable bag and a skirt between a heat seal and an edge of the bag. The bag is made from a multilayer film with at least one film layer comprising an incompatible polymer blend so that after shrinking the film exhibits controlled tear direction. The bag skirt has a bag tear initiator for initiating a controlled direction tear to the opposite side of the bag. The patch has an edge with a patch tear initiator separated from the bag tear initiator but positioned along a tear line emanating from bag tear initiator, so that upon tearing the shrunken bag, the controlled tear propagates into the patch tear initiator and thereafter the shrunken bag and the shrunken patch tear together towards an opposite edge of the patch.

BACKGROUND

The present invention pertains to heat-shrinkable patch bags that areeasy to open, particularly for the packaging of bone-in meat products.

For several decades, heat-shrinkable bags have been used for thepackaging of a variety of products, particularly food. Patch bags cameinto use over twenty years ago for the packaging of bone-in meatproducts. A patch bag has a patch adhered to the bag, with the patchproviding additional reinforcement where a bone end contacts the bag.The bone end can be aggressive with respect to package integrity.Supplementing the bag with a patch has proven to be effective inreducing leaker rates for the packaging of bone-in meat products.

Heat shrinkable bags used in the meat packaging industry have, overtime, developed higher impact strength and higher seal strength, whilesimultaneously becoming easier to seal, having improved oxygen andmoisture barrier properties, and having higher total free shrink atlower temperatures. High seal strength, high impact strength, and highpuncture-resistance are particularly important for the packaging offresh meat products, as leaking packages are undesirable to consumersand retailers. Moreover, leaking packages reduce shelf life by allowingatmospheric oxygen and microbes to enter the package.

As a result, the bags used for food packaging, particularly meatpackaging, have become tougher and more difficult to open. Typically,knives and scissors are used for opening the bags that have beenevacuated, sealed around, and shrunken against the food product in thepackage. The use of knives and scissors to open these tough bagsincreases the risk of injury for consumers and retailers. Moreover, theopening of such tough packaging requires more time and effort due to thetoughness of the shrunken bag.

Tough heat shrinkable bags with tear initiators and controlled teardirection have entered the marketplace over the last few years. Whilethese bags allow for easy opening without the problems arising from theuse of knives or scissors, such bags having patch thereon have had a bagtear initiator placed along the side edge of the bag, i.e., so that thetear does not run into the patch, but runs along the side of the patch,and also along the side edge of the bag. It has been found that suchtearing does not open the bag wide enough to facilitate removal of theproduct from the bag. However, if a more centrally-positioned bag tearinitiator is positioned so that the bag tear propagates into the patchadhered to the bag, the patch does not tear with the bag, and as aresult the tear force must be increased considerably as bag continues totear, with the stressed portion of the patch initially stretching, andthe application of further tearing force resulting in a substantialportion of the patch delaminating from the bag. It would be desirable toprovide a heat shrinkable patch bag with a bag tear initiator notcovered by the patch, that after shrinking can be opened by the manualinitiation and propagation of a controlled direction tear thatpropagates into the patch and thereafter tears the patch and bagtogether down the length of the bag to the opposite edge of the bag insuch a manner that the product can be easily removed from the bag.

SUMMARY

The heat-shrinkable patch bag of the invention has a bag tear initiatorthat can be used to concentrate tearing force for initiating a manualtear of the bag, with the tear direction being controlled by anincompatible polymer blend in at least one layer of the multilayer bagfilm. The bag tear initiator is separated from the patch, i.e., thepatch does not extend to or cover the bag tear initiator. As the bag istorn, the controlled direction bag tear propagates towards the patch andmore particularly, towards the patch tear initiator, along a lineextending into the patch tear initiator. Unlike the making of a patchbag having a tear initiator that passes through both the bag and thepatch, the separation of the patch tear initiator from the bag tearinitiator requires the patch to be provided with its tear initiatorbefore the patch is adhered to the bag. Moreover, the patch tearinitiator must be placed along the bag tear line so that the bag tearpropagates into the patch tear initiator. Once the bag tear propagatesinto the patch tear initiator, thereafter the bag and patch teartogether, with the patch tearing to an edge opposite the patch edgehaving the patch tear initiator, and the bag tearing to an edge oppositethe bag edge having the bag tear initiator.

A first aspect is directed to a patch bag comprising a heat-shrinkablepatch adhered to a heat-shrinkable bag. The bag has an open top and atop edge, a closed bottom and a bottom edge, a first side edge, a secondside edge, a first lay-flat side, a second lay-flat side, a heat seal ofa region of the first lay-flat side to a region of the second lay-flatside, a first tear initiator in the first lay-flat side in a bag skirtoutward of the heat seal or in a bag header between the patch and thetop edge of the bag, a second tear initiator in the second lay-flat sidein the bag skirt outward of the heat seal or in the bag header betweenthe patch and the top edge of the bag. At least a portion of theheat-shrinkable patch is adhered to an outside surface of the firstlay-flat side of the bag. The patch has a patch tear initiator locatedon an edge of the patch in a location separated from the first bag tearinitiator. The patch tear initiator is aligned with an MD or TD tearline extending from the first bag tear initiator. The heat shrinkablebag comprising a multilayer film having at least one layer comprising anincompatible polymer blend.

In an embodiment, the incompatible polymer blend comprises at least onemember selected from the group consisting of: (A) a blend of from 90 to30 wt % ethylene homopolymer and/or ethylene/α-olefin copolymer withfrom 10 to 70 wt % ethylene/unsaturated ester copolymer having anunsaturated ester content of at least 10 wt %; (B) a blend of ionomerresin with ethylene/unsaturated ester copolymer, and/or polybutylene,and/or propylene homopolymer and/or propylene copolymer; (C) a blend ofhomogeneous ethylene/α-olefin copolymer with recycled polymer blendcomprising ethylene homopolymer, propylene homopolymer, ethylenecopolymer, propylene copolymer, polyamide, ethylene/vinyl alcoholcopolymer, ionomer resin, anhydride-modified ethylene/α-olefincopolymer, and/or antiblock; (D) a blend of from 10 to 75 wt %ethylene/unsaturated ester copolymer with from 90 to 15 wt %polypropylene and/or propylene/ethylene copolymer, and/or polybutylene,and/or modified ethylene/α-olefin copolymer, and/or styrene homopolymer,and/or styrene/butadiene copolymer; (E) a blend of ethylene/norbornenecopolymer with ethylene/unsaturated ester copolymer and/or polypropyleneand/or polybutylene; (F) a blend of from 90 to 15 wt % ethylene/α-olefincopolymer with from 10 to 75 wt % polypropylene and/or polybutyleneand/or ethylene/norbornene; (G) a blend of from 90 to 25 wt %homogeneous propylene homopolymer and/or homogeneous propylene copolymerwith from 10 to 75 wt % homogeneous ethylene/α-olefin copolymer and/orethylene/unsaturated ester copolymer; (H) a blend of propylenehomopolymer and/or propylene/ethylene copolymer and/or polybutylene withethylene/methyl acrylate copolymer and/or ethylene/acrylic acidcopolymer and/or ethylene/butyl acrylate copolymer; (I) a blend ofpolyamide with polystyrene and/or ethylene/α-olefin copolymer and/orethylene/vinyl acetate copolymer and/or styrene/butadiene copolymer; (J)a blend of polyamide 6 and polyamide 6I6T; (K) a blend of athermoplastic polymer and a filler, wherein the filler is present in anamount of at least 5 wt %, based on layer weight.

In an embodiment, the bag is an end-seal bag comprising a seamlesstubing with the first and second bag side edges being folded edges, withthe heat seal being an end seal across a bottom of the bag, with theskirt being outward of the end seal, with the patch tear initiator beingaligned with the MD tear line extending from the first tear initiator.

In another embodiment, the bag is a side-seal bag having an open top, afolded bottom edge, first side seal along the first side edge, secondside seal along the second side edge, with respective first and secondbag skirts outward of respective first and second side seals, with thefirst and second tear initiators being in the first bag skirt andoutward of the first side seal, with the patch tear initiator beingaligned with the MD tear line extending from the first tear initiator.

In another embodiment, the bag is a pouch having a bottom seal which isa heat seal of the first lay-flat side to the second lay-flat side alongthe bottom edge, with a bottom skirt between the bottom edge and thebottom seal, and a first side seal which is a heat seal of the firstlay-flat side to the second lay-flat side along the first side edge witha first side skirt between the first side seal and the first side edge,a second side seal which is a heat seal of the first lay-flat side tothe second lay-flat side along the second side edge with a second sideskirt between the second side seal and the second side edge, with thefirst and second tear initiators being in the same skirt.

In another embodiment, the bag is a backseamed bag having a bottom sealwhich is a heat seal of the first lay-flat side to the second lay-flatside along the bottom edge, with a bottom skirt between the bottom edgeand the bottom seal, with the backseamed bag having a backseamed sealwhich is a heat seal of the multilayer film to itself, with the backseamseal being on the second lay-flat side of the bag and the backseamrunning from the bottom edge of the bag to the top edge of the bag.

In an embodiment, the patch comprises a plurality of tear initiators,with one of the tear initiators being aligned with an MD or TD tear lineextending from the first bag tear initiator. In an embodiment, the patchtear initiator is V-shaped or Y-shaped.

In an embodiment, the bag film is a multilayer film comprising an outerseal and meat contact layer which is an inside layer of the bag andwhich comprises ethylene/α-olefin copolymer, an outer abuse layer whichis an outside layer of the bag and which comprises ethylene/α-olefincopolymer, an internal O₂-barrier layer, a first tie layer between theseal layer and the O₂-barrier layer, a second tie layer between theO₂-barrier layer and the abuse layer, a first incompatible polymer blendlayer between the seal layer and the first tie layer, and a secondincompatible polymer blend layer between the abuse layer and the secondtie layer, wherein first and second incompatible polymer blend layerscomprise a blend of from 60 to 80 wt % ethylene/α-olefin copolymer and40 to 20 wt % ethylene/unsaturated ester copolymer having an unsaturatedester content of at least 10 wt %, based on polymer weight, with theamount of incompatible polymer blend in the film being from 30 to 70 wt%, based on total film weight, and the patch comprises self-weldedmultilayer film having an outer layer comprising ethylene/α-olefincopolymer, self-weld layer comprising an ethylene unsaturated ester orethylene/unsaturated acid copolymer, and an intermediate layer betweenthe self weld layer and the outer layer comprising ethylene/α-olefincopolymer.

In an embodiment, the entirety of the patch is positioned inward of theheat seal, with no portion of the patch extending to the heat seal. Inan alternative embodiment, the patch covers at least a portion of theheat seal and a portion of the patch covers a portion of the skirt, withthe portion of the patch covering the skirt having an edge which isinside an outer edge of the skirt.

In an embodiment, the skirt further comprises a grip assister, and atleast a portion of the skirt or header is heatset in order to reduce theshrinkage of the skirt or header upon shrinking the film around theproduct. In an embodiment, the heatset portion comprises at least onesupplemental heat seal of at least a portion of the first lay-flat sideof the skirt to a portion of the second lay-flat second side of theskirt.

In an embodiment, the multilayer film has Peak Load Impact Strength,determined using ASTM D 3763-95A, of at least 50 Newtons per mil, andthe multilayer film has thickness of from 1.5 to 5 mils.

In an embodiment, the patch is provided with a line of weakness alignedalong a tear line aligned with and extending from the patch tearinitiator. In another embodiment, the patch does not have a line ofweakness aligned with the patch tear initiator. In another embodiment,the bag does not have a line of weakness aligned and extending from thebag tear initiator. In an embodiment, neither the bag nor the patch hasa line of weakness aligned with and extending from the respective bagand patch tear initiators.

In an embodiment, the first tear initiator and the second tear initiatorare coincident (directly on top of one another when the bag is in itslay-flat configuration) or substantially coincident. Alternatively, thefirst tear initiator can overlap the second tear initiator to at leastsome extent when the bag is in its lay-flat configuration.

In an embodiment, the patch comprises a heat shrinkable film that doesnot comprise an incompatible polymer blend and does not comprise afiller. In an alternative embodiment, the patch comprises a heatshrinkable film containing an incompatible polymer blend.

A second aspect is directed to a process for making an easy-openpackaged product, comprising: (A) inserting a product into a lay-flatpackaging article in accordance with the first aspect, and any specificembodiments thereof; (B) evacuating the atmosphere from inside thepackaging article; (C) sealing the packaging article closed with atleast one heat seal, thereby forming a packaged product in which apackage surrounds the product; and (D) shrinking the heat-shrinkablefilm to shrink the package around the product.

In an embodiment, the process further comprises manually opening thepackage by manually initiating tears from the first and second tearinitiators.

In an embodiment, the process can be carried out on a plurality ofheat-shrinkable patch bags in a continuous strand, each of the patchbags being connected to an adjacent patch bag along a weakened tearline.

In an embodiment, the tear initiator can be placed in the top edge ofthe bag before or after the product is placed into the bag. In anembodiment, the tear initiator can be placed in the top edge of the bagduring or after the sealing to close the bag with the product inside thebag. In an embodiment, the tear initiator can be placed in a top edge ofthe bag as the top edge is made during cutting to remove excess bagheader after the bag is sealed closed with the product inside the bag.

A third aspect is directed to a process carried out on a continuousstrand of the multilayer film from which the bag is made, the strandhaving patches adhered to intermittently. The strand with patchesthereon is wrapped around a bone-in meat product and a backseam heatseal (fin-type or lap-type) made followed by making the transversebottom seal, with the resulting patch bag (having the meat producttherein) being separated from the strand and the atmosphere thereafterevacuated from inside of the bag and the bag sealed closed and shrunkaround the meat product. The patch bag can be in accordance with any ofthe embodiments in accordance with the first aspect, above.

A fourth aspect is directed to a process for making a package andmanually opening the package, by (A) placing a product inside aheat-shrinkable patch bag according to the first aspect above, (B)sealing the bag closed so that a package is formed, and (C) manuallyinitiating and manually propagating a first tear in the first side ofthe bag, and a second tear in the second side of the bag, with the firsttear propagating to an edge of a patch adhered to the bag, with thefirst tear propagating into a tear initiator along the edge of thepatch, with the bag and patch tearing together to an opposite edge ofthe patch, so that the so that the product can be readily removed fromthe bag. The process can be carried out with or without the additionalsteps of (D) evacuating the atmosphere from inside the bag beforesealing the bag closed, and/or (E) shrinking the package around theproduct after sealing the bag closed. The patch bag can be in accordancewith any of the embodiments in accordance with the first aspect, above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a heat-shrinkable end-seal patch bag inlay-flat configuration.

FIG. 2 is a schematic of a cross-sectional view of the patch bag of FIG.1, taken through section 2-2 of FIG. 1.

FIG. 3 a schematic of a heat-shrinkable side-seal bag in lay-flatconfiguration.

FIG. 4 is a schematic of a cross-sectional view of the patch bag of FIG.3, taken through section 4-4 of FIG. 3.

FIG. 5 is a schematic of a heat-shrinkable pouch-style patch bag inlay-flat configuration.

FIG. 6A is a schematic of a heat-shrinkable backseamed patch bag inlay-flat configuration.

FIG. 6B is a schematic of a cross-sectional view of the patch bag ofFIG. 6A, taken through section 6B-6B of FIG. 6A.

FIG. 7 is a schematic of an alternative heat-shrinkable end-seal patchbag in lay-flat configuration.

FIG. 8 is a perspective view of a packaged product made from aheat-shrinkable end-seal patch bag.

FIG. 9 is a schematic view of an extrusion coating process used to makemultilayer heat-shrinkable films.

FIG. 10 is a schematic view of a coextrusion process used to makemultilayer heat-shrinkable films.

DETAILED DESCRIPTION

As used herein, the term “film” is inclusive of plastic web, regardlessof whether it is film or sheet. The film from which the bag is made canhave a total thickness of 0.25 mm or less, or a thickness of from 1.5mils to 10 mils, or from 1.5 to 5 mils, or from 1.8 mils to 4 mils, orfrom 2 mils to 3 mils. The film from which the patch is made can have athickness of from 2 to 10 mils, or from 2 to 8 mils, or from 2 to 6mils, or from 3 to 5 mils.

The multilayer, heat-shrinkable film from which the bag is made canexhibit a Peak Load Impact Strength, determined using ASTM D 3763-95A,of at least 50 Newtons per mil. ASTM D 3763-95A is hereby incorporated,in its entirety, by reference thereto. The heat-shrinkable bag film canhave a Peak Load Impact Strength, determined using ASTM 3763-95A, offrom 50 to 250 Newtons per mil, or from 60 to 200 Newtons per mil, orfrom 70 to 170 Newtons per mil; or from 80 to 150 Newtons per mil; orfrom 85 to 140 Newtons per mil; or from 95 to 135 Newtons per mil.

As used herein, the phrase “machine direction” refers to the directionin which the film emerges from the die. Of course, this directioncorresponds with the direction the extrudate is forwarded during thefilm production process. The phrase “machine direction” corresponds with“longitudinal direction”. Machine direction and longitudinal directionare abbreviated as “MD” and “LD”, respectfully. However, as used herein,the phrase “machine direction” includes not only the direction along afilm that corresponds with the direction the film traveled as it passedover idler rollers in the film production process, it also includesdirections that deviate up to 44 degrees from the direction the filmtraveled as it passed over idler rollers in the production process.

As used herein, the phrase “transverse direction” refers to a directionperpendicular to the machine direction. Transverse direction isabbreviated as “TD”. The transverse direction also includes directionsthat deviate up to 44 degrees from the direction the film traveled as itpassed over idler rollers in the production process.

As used herein, the term “bag” refers to a packaging article having anopen top, side edges, and a bottom edge. The term “bag” encompasseslay-flat bags, pouches, casings (seamless casings and backseamedcasings, including lap-sealed casings, fin-sealed casings, andbutt-sealed backseamed casings having backseaming tape thereon). Variouscasing configurations are disclosed in U.S. Pat. No. 6,764,729 B2, toRamesh et al, entitled “Backseamed Casing and Packaged ProductIncorporating Same”, which is hereby incorporated in its entirety, byreference thereto.

The term “bag” also includes that portion of a package that is derivedfrom a bag. That is, once a product is placed inside a bag, the bag issealed closed so that it surrounds the product. Excess bag length (i.e.,the “bag tail”, or “bag header”) can optionally be cut off along a lineclose to the seal made across the bag to enclose the product within thebag, and thereafter optionally the film can be shrunk around theproduct. The portion of the bag that remains and is configured aroundthe product is herein also within the term “bag”. The phrase “anopposite bag edge” refers to the edge of the bag that is directly acrossfrom the bag edge having the tear initiator. For example, a bag top edgeis opposite the bag bottom edge; a first bag side edge is opposite thesecond bag side edge. As used herein, the phrase “a side of the bag” isused with reference to each of the first and second sides of a lay-flatbag, as well as each of the two principal, flat sides of a gusseted bag.

As used herein, the phrase “bag skirt,” and the term “skirt,” refer tothat portion of a bag that is outward of a heat seal, i.e., the excessbag length or width on the non-product side of the heat seal. In anend-seal bag, the bag skirt is short in the machine direction and longin the transverse direction. In a side-seal bag, the bag skirt is alsolong in the transverse direction and short in the machine direction, dueto the manner in which side-seal bags are made from extrudedheat-shrinkable film tubing. In either case, the “width” of the bagskirt is the shorter dimension of the skirt, and the “length” of the bagskirt is the longer dimension of the skirt. A bag skirt can have awidth, before the film is shrunk, of at least 5 millimeters, or at least10 millimeters, or at least 15 millimeters, or at least 20 millimeters,or at least 25 millimeters, or at least 30 millimeters. The bag skirtcan have a width of from 5 to 100 millimeters, or from 10 to 50millimeters, or from 15 to 40 millimeters, or from 20 to 35 millimeters.

As used herein, the phrase “lay-flat bag” refers generically to bagsused for the packaging of a variety of products, particularly foodproducts. More specifically, the phrase “lay-flat bag” includes sideseal bag, end-seal bag, L-seal bag, U-seal bag (also referred to as apouch), and backseamed bag (also referred to as T-seal bag). Thebackseam can be a fin seal, a lap seal, or a butt-seal with abackseaming tape. Before the bag is shrunk, it can have alength-to-width ratio of from 1:1 to 20:1; or from 1.5:1 to 8:1; or from1.8:1 to 6:1; or from 2:1 to 4:1.

The tear initiator can be a cut in the bag skirt. As used herein, theterm “cut” refers to the penetration through the film, or shearingthrough the film, e.g., with scissors, knife, sharpened punch, etc. Theterm “cut” is inclusive of both slits and notches. As used herein, theterm “slit” refers to a cut through the film without the separation andremoval of a piece of film from the bag. A slit can be from the edge ofthe bag (i.e., an “edge slit”) or internal, i.e., not extending to anedge (i.e., “internal slit” also referred to as a “slit hole”). The slitcan be straight or curved or wavy. Both “V” shaped and “Y” shaped tearinitiators are useful in both the bag and the patch. The Y-shaped tearinitiator is a combination of a notch and a slit.

The term “hole”, as used herein, includes both an internal puncture(i.e., internal hole) or internal cut (i.e., an internal slit) throughthe packaging article, as well as an internal cut that removes a pieceof film from the article. The hole can utilize a straight cut or acurved cut. The hole can be round or square or rectangular or irregularin shape.

A “notch” is formed by a cut that removes a piece of film along anotherwise straight or smooth curved edge of a bag skirt or a bag tail,producing a point for stress concentration during the subsequent manualapplication of tearing force. A notch can be V-shaped or round or squareor rectangular or oval or of any regular or irregular profile.

The slit or notch or hole in the bag skirt can extend across at least 10percent of the width of the bag skirt before the bag is shrunk; or atleast 20 percent, or at least 30 percent or at least 40 percent, or atleast 50 percent, or at least 60 percent, or at least 70 percent, or atleast 80 percent, or at least 90 percent, of the width of the bag skirtor bag tail. The slit or notch or hole can angle inward, toward the bagcenter.

In end-seal and side-seal bags, a portion of a bag skirt is in a firstlay-flat side of the bag, and a portion of the same bag skirt is in asecond lay-flat side of the bag. The first lay-flat side of the bagskirt can have a first tear initiator, and the second lay-flat side ofthe bag can have a second tear initiator.

The first tear initiator can overlap the second tear initiator when theend-seal or side-seal bag (or any other bag) is in its lay-flatconfiguration, as well as in the shrunken package. Overlapping enhancesthe ease of simultaneously initiating and propagating the tears in thefirst and second sides of the bags. Moreover, the first tear initiatorcan coincide (i.e., be positioned directly over, and correspond inlength and shape) with the second tear initiator when the bag is in itslay-flat configuration.

As used herein, the verb “to tear” refers to pulling an object apart byforce. The noun “tear” refers to the resulting break in the object beingtorn. The tearing of the film results from placing the film under enoughtension that it is pulled apart by the force. The pulling force isconcentrated by the tear initiator, which allows a smaller pulling forceto pull the film apart, i.e., tear the film. It is not easy to manuallytear a high impact strength heat-shrinkable film in the absence of atear initiator. In the heat-shrinkable bag, the high impact strengthmultilayer film undergoes tearing from the tear initiator toward theopposite edge of the bag. The tearing is carried out by gripping theskirt and exerting a manual tearing force, without regripping thepackage during the process of tearing, so that the tear direction isdetermined by the direction the bag and patch naturally tear along. Thetear direction is controlled by the presence of the incompatible polymerblend in the film. The incompatible polymer blend causes a controlledtear of the bag, and thereafter of the patch, towards their respectiveopposite edges. As used herein, the phrase “to the opposite edge” isused with respect to a controlled direction tear which, in the ordinarycourse of tearing as described herein, naturally propagates towards theopposite edge of the bag or patch. Moreover, a tear which naturallypropagates towards the opposite edge is a tear which propagates to theopposite edge if the tear is propagated to the extent that the film orpackage is torn into two discrete pieces.

The phrase “tear initiator”, as used herein, refers to any one or moreof a variety of notches or cuts that can be located in the bag skirt oralong the edge of the patch. Tear initiators allow manual tearing forceto be concentrated on a point or small region of the film(s), so thattear initiation and tear propagation can be produced manually. A slit inthe bag skirt and/or patch can serve as the tear initiator.Alternatively, the tear initiators include U-shaped notch (and multipleU-shaped notches such as from two to fifty U-shaped notches spaced closeto one another), V-shaped notch (and multiple V-shaped notches such asfrom two to fifty V-shaped notches side-by-side, for example as thezigzag or saw tooth pattern produced with, for example, pinking shears),or Y-shaped notch-cut combination (and multiples thereof, such as two tofifty Y-shaped notches), as well as a wide variety of tear initiatorembodiments useful in both bags and patches, are disclosed in US2009/0116768 A1, published 7 May 2009, entitled “Easy Opening PackagingArticle Made From Heat Shrinkable Film Exhibiting Directional Tear,”hereby incorporated, in its entirety, by reference thereto.

If the tear initiator is placed in a location of the bag so that thetear is initiated and propagated into a portion of the bag not coveredby the patch, then the patch need not have a tear initiator. However,because most patch bags have large patches extending over a majority ofthe bag, locating the bag tear initiators along a side edge of anend-seal bag, or along a bottom edge of a side-seal bag, etc, i.e., toproduce a tear along a tear line that propagates into the region of thebag covered by the patch, results in the tearing off of only a smallstrip of film (because the tears in each lay-flat side of the bag areclose to one another), with the product being difficult to remove fromthe package after the tear is complete. Rounded products, such a wholebirds (turkeys, chickens, etc), hams, etc., are particularly difficultto remove if only a small strip of film is torn off of the package.

This problem could be addressed by moving the bag tear initiator to thecenter of the bag with the bag and patch tear initiators beingcoincident, so that the tear of the patch and bag together results, ineffect, in the bag tearing into halves, making it easier to remove theproduct from the package, particularly rounded products such as wholebirds, hams, etc. However, this solution requires the patch to tear withthe bag. If the tear initiators of the patch and bag are coincident, thepatch must cover the heat seal, which produces further challenges as itis difficult, and slower, to make a heat seal of the bag to itself byapplying heat through the patch. Having the patch tear initiatorseparated from, but aligned with, the bag tear initiator allows for thedesirable combination of (i) a patch which does not cover the heat seal(so that the heat seal need not be made through the patch), and (ii) abag tear initiator positioned at a location for tearing the bag down acenterline (or central region of the package) in order that the productcan be easily removed from the torn-open package.

A tear line is down a centerline of an end-seal bag or pouch if the tearline is an MD tear line located 50% of the distance across the width ofa package made from the end-seal bag or pouch. A tear line is down acenterline of a side-seal bag if the tear line is an MD tear linelocated 50% of the distance between the folded bottom edge and the topseal of a package made from the side-seal bag. A tear line is down acenterline of a pouch if the tear line is a TD tear line located 50% ofthe distance between the bottom seal and top seal of the package madefrom a pouch.

As used herein, the phrase “central region” refers to a region broaderthan the centerline, i.e., a region running the length of thecenterline, centered over the centerline, and extending outwardly fromthe centerline for a total distance of up to 10% of the full bag orpouch dimension transverse to the centerline (i.e., up to 5% on eachside of the centerline), or up to 20%, or up to 30%, or up to 40%, or upto 50%, or up to 60%, or up to 70% of the full bag or pouch dimensiontransverse to the centerline. The placement of the bag tear initiator inthe central region, and the alignment of the patch tear initiator withthe bag tear initiator, allows tearing of the bag and patch so that upontearing the package open the product can be readily removed. Of course,the patch tears with the bag as a result of the alignment of the patchtear initiator with the tear line extending from the bag tear initiator.

In addition to the tear initiator, the bag can be provided with one ormore grip assisters. Grip assisters enhance the ease of tearing of thebag, and with the propagation of the tear to the patch, the gripassisters enhance the ease of tearing the bag and patch together. Thegrip assisters can be in one lay-flat side of the bag, but preferablyare in both lay-flat sides of the bag. The grip assisters can be a holein the bag skirt (and/or in the bag tail), in an extension of the bagskirt (and/or the bag tail), or a separate film tab fastened to the bagskirt (and/or the bag tail). A hole can be made in the bag skirt bymaking a cut that completely surrounds and separates that portion of thefilm inside the hole, or by making a cut that partially surrounds aportion of the film, leaving a hanging chad in place. In the latter gripassister, there is no need to remove the piece of film, and thereby lesschance of contaminating the product with a relatively small, separatedpiece of film. If a separate film tab is used as the grip assister, thetab can be made from a thermoplastic polymer, paper, or other material,and can be heat-shrinkable, but is preferably non-heat-shrinkable.Various grip assisters are also disclosed in US 2009/0116768 A1.

With respect to the tearing of the film from which the bag is made, asused herein the phrase “the tear is capable of being propagated . . . ”refers to the manner in which the film tends to propagate the tear whenthe bag is subjected to an ordinary manual opening thereof, i.e., thebag being “gripped and ripped” in the ordinary course of opening. Thebag tends to exhibit linear tear. Usually, the tear is substantially inline with the machine direction or substantially in line with thetransverse direction.

If the tear is being made in the machine direction of the film, the tearmay be within from 0 to 44 degrees of the actual machine direction ofthe film, i.e., so long as the tear can be propagated toward and to theopposite side edge of the bag; or the tear may be within from 0 to 20degrees, or within from 0 to 15 degrees, or within from 1 to 20 degrees,or within from 0 to 10 degrees; or within from 0 to 5 degrees, or withinfrom 0 to 2 degrees of the machine direction of the film or within 0 to1 degree. The same holds true of transverse direction tearing, i.e., thetear may be within from 0 to 44 degrees of the actual transversedirection of the film; or the tear may be within 0 to 20 degrees, orwithin 1 to 20 degrees, or within from 0 to 10 degrees; or within from 0to 5 degrees, or within from 0 to 2 degrees of the transverse directionof the film; or within 0 to 1 degree.

The combination of the tear initiators and the presence of at least onefilm layer comprising an incompatible polymer blend provides the bagfilm with the capability of having a manually-initiated,manually-propagated first tear in the first side of the bag, and amanually-initiated and manually-propagated second tear in the secondside of the bag, the first tear and the second tear each being capableof being propagated from the respective first and second tearinitiators, with each tear being propagated across the bag, or down thelength of the bag, with the tears being capable of being manuallypropagated through and to an opposite bag edge. At least one of thetears propagates along a tear line extending into a patch tear initiatoralong an edge of a patch adhered to the bag, with the patch and bagthereafter tearing together, so that upon making a package by placing aproduct inside the bag, sealing the bag closed so that a package isformed, and shrinking the film around the product, the resulting packagecan be manually opened, and the product readily removed from the bag, bymanually initiating tears from the first and second tear initiators andthe patch tear initiator, with the bag tears being manually propagatedthrough the heat seal, to the opposite edge of the patch, and to theopposite edge of the bag, and with the patch tear being manuallypropagated to the opposite edge of the patch.

As used herein, the phrases “seal layer,” “sealing layer,” “heat seallayer,” and “sealant layer,” refer to an outer film layer, or layers,involved in heat sealing of a first region of the film to: (i) a secondregion of the same film (which in a multilayer film can be the sameouter layer, e.g., fin seal, or the opposite outer layer, e.g., lapseal), (ii) a region of another film, and/or (iii) another article whichis not a film.

Heat sealing can be performed in any one or more of a wide variety ofmanners, such as melt-bead sealing, thermal sealing, impulse sealing,ultrasonic sealing, hot air sealing, hot wire sealing, infraredradiation sealing, ultraviolet radiation sealing, electron beam sealing,etc.). A heat seal is usually a relatively narrow seal (e.g., 0.02 inchto 1 inch wide) across a film. An impulse sealer uses a combination ofheat and pressure to form the heat seal, with the heating meansproviding a brief pulse of heat while pressure is being applied to thefilm by a seal bar or seal wire, followed by rapid cooling.

In some embodiments, the seal layer can comprise a polyolefin,particularly an ethylene/α-olefin copolymer. For example, the seal layercan contain a polyolefin having a density of from 0.88 g/cc to 0.917g/cc, or from 0.90 glee to 0.917 glee. The polyolefin can be anethylene/α-olefin copolymer. More particularly, the seal layer cancomprise at least one member selected from the group consisting of verylow density polyethylene and homogeneous ethylene/α-olefin copolymer.Very low density polyethylene is a species of heterogeneousethylene/α-olefin copolymer. The heterogeneous ethylene/α-olefin (e.g.,very low density polyethylene) can have a density of from 0.900 to 0.917g/cm³, and the homogeneous ethylene/α-olefin copolymer can have adensity of from 0.880 g/cm³ to 0.910 g/cm³, or from 0.880 g/cm³ to 0.917g/cm³. The polyolefin can be an ionomer resin or an ethylene/α-olefincopolymer. Metallocene-catalyzed sealants with densities of 0.917 g/cm³or less, as well as a very low density polyethylene having a density of0.912 g/cm³, provided excellent optics. Plastomer-type metallocenesealants with densities less than 0.910 g/cm³ also provided excellentoptics.

In an embodiment, the bag can have a heat seal capable of withstanding atemperature of at least 70° C. for a period of at least 4 hours, withthe patch being adhered to the bag with an adhesive capable ofmaintaining adhesion of the patch to the bag at a temperature of atleast 97° C. for a period of at least 10 minutes, as disclosed in U.S.Pat. No. 7,338,691 B2, entitled “Cook-In Patch Bag and Process for UsingSame,” which is hereby incorporated, in its entirety, by referencethereto.

As used herein, the term “barrier”, and the phrase “barrier layer”, asapplied to films and/or film layers, are used with reference to theability of a film or film layer to serve as a barrier to one or moregases. In the packaging art, oxygen (i.e., gaseous O₂) barrier layerscan comprise, for example, at least one member selected from the groupconsisting of hydrolyzed ethylene/vinyl acetate copolymer (designated bythe abbreviations “EVOH” and “HEVA”, and also referred to as “saponifiedethylene/vinyl acetate copolymer” and “ethylene/vinyl alcoholcopolymer”), polyvinylidene chloride, amorphous polyamide, polyamideMXD6 (particularly MXD6/MXDI copolymer), polyester, polyacrylonitrile,etc., as known to those of skill in the art. In addition to the firstand second layers, the heat-shrinkable film may further comprise atleast one barrier layer.

The heat-shrinkable multilayer film from which the bag is made canexhibit O₂-transmission rate of from 1 to 20 cc/m² day atm at 23° C. and100% relative humidity, or from 2 to 15 cc/m² day atm at 23° C. and 100%relative humidity, or from 3 to 12 cc/m² day atm at 23° C. and 100%relative humidity, or from 4 to 10 cc/m² day atm at 23° C. and 100%relative humidity. Alternatively, the heat-shrinkable film can exhibitan O₂-transmission rate of from 21 cc/m² day atm to 15,000 cc/m² dayatm, or from 500 cc/m² day atm to 10,000 cc/m² day atm, or from 2000cc/m² day atm to 6,000 cc/m² day atm.

As used herein, the phrase “tie layer” refers to any internal layerhaving the primary purpose of adhering two layers to one another. Tielayers can comprise any polymer having a polar group grafted thereon.Such polymers adhere to both nonpolar polymers such as polyolefin, aswell as polar polymers such as polyamide and ethylene/vinyl alcoholcopolymer. Tie layers can comprise at least one member selected from thegroup consisting of polyolefin (particularly homogeneousethylene/α-olefin copolymer), anhydride-modified polyolefin,ethylene/vinyl acetate copolymer, and anhydride-modified ethylene/vinylacetate copolymer, ethylene/acrylic acid copolymer, and ethylene/methylacrylate copolymer. Typical tie layer polymers comprise at least onemember selected from the group consisting of anhydride modified linearlow density polyethylene, anhydride modified low density polyethylene,anhydride modified polypropylene, anhydride modified methyl acrylatecopolymer, anhydride modified butyl acrylate copolymer, homogeneousethylene/α-olefin copolymer, and anhydride modified ethylene/vinylacetate copolymer.

As used herein, the phrases “inner layer” and “internal layer” refer toany layer, of a multilayer film, having both of its principal surfacesdirectly adhered to another layer of the film.

As used herein, the phrase “outer layer” refers to any film layer havingless than two of its principal surfaces directly adhered to anotherlayer of the film. A multilayer film has two outer layers, each of whichhas a principal surface adhered to only one other layer of themultilayer film.

Once a multilayer film is heat sealed to itself or another member of thepackage being produced (i.e., is converted into a packaging article,e.g., a bag, pouch, or casing), one outer layer of the film is an insidelayer of the packaging article and the other outer layer becomes theoutside layer of the packaging article. The inside layer can be referredto as an “inside heat seal/product contact layer”, because this is thefilm layer that is sealed to itself or another article, and it is thefilm layer closest to the product, relative to the other layers of thefilm. The other outer layer can be referred to as the “outside layer”and/or as the “outer abuse layer” or “outer skin layer”, as it is thefilm layer furthest from the product, relative to the other layers ofthe multilayer film. Likewise, the “outside surface” of a packagingarticle (i.e., bag) is the surface away from the product being packagedwithin the bag.

The heat-shrinkable patch film is laminated to the outside surface ofthe film from which the bag is made. The patch can be laminated in anyknown manner, for example using an adhesive or a heat seal or coronatreatment. A liquid adhesive is applied to the surface of the patchwhich is to be adhered to the outside surface of the bag. A preferredadhesive is a thermoplastic acrylic emulsion known as RHOPLEX N619™thermoplastic acrylic emulsion, obtained from the Rohm & Haas Company,at Dominion Plaza Suite 545, 17304 Preston Rd., Dallas, Tex. 75252, Rohm& Haas having headquarters at 7th floor, Independence Mall West,Philadelphia, Pa. 19105. The lamination of the patch to the bag can becarried out as described in U.S. Pat. No. 6,790,468, to Mize et al,entitled “Patch Bag and Process of Making Same”, which is herebyincorporated, in its entirety, by reference thereto.

The patch film can be heat-shrinkable, and can have a total free shrinkat 185° F. of at least 35 percent, measured in accordance with ASTMD-2732. The bag film and the patch film can have a total free shrink at185° F. that are within 50 percent of one another, or within 20 percentof one another, or with 10 percent of one another, or within 5 percentof one another, or within 2 percent of one another. The patch may besized and positioned so that it is inward of the seal and does notextend to the heat seal; alternatively, the patch may be sized andpositioned so that it covers one or more heat seals. If the patch coversa heat seal, optionally the heat seal may be made through the patch, orthe seal may be made through the bag film only, with the patch beingadhered over the seal after the seal is made. The bag can have a curvedseal and the patch can extend into and through the region of the curvedseal and over and past the curved seal. If the bottom edge of the bag iscurved, a bottom edge of the patch can also be curved. The patch bag canhave any desired configuration of patch on bag as disclosed in any oneor more of U.S. Pat. Nos. 4,755,403, 5,540,646, 5,545,419, 6,296,886,6,383,537, 6,663,905, and 6,790,468, each of which is herebyincorporated, in its entirety, by reference thereto.

The patch can be monolayer or multilayer. In an embodiment, the patch ismade from a heat-shrinkable film tubing that is collapsed onto itselfinto lay-flat configuration with the inside surface of the tubingself-welding to form a multilayer flat patch film having a symmetricalcross-sectional layer arrangement. In this process, a sufficient amountof powdered cornstarch or other inert powder is applied to the interiorof the tubular extrudate so that upon collapsing, the tube will not selfadhere, but after opening, heating, and stretching the tube to biaxiallyorient the tube material and thereafter collapsing and flattening theoriented tubing, the oriented tubing adheres to itself, i.e.,self-welds. The resulting self welded multilayer film is thereafter cutinto a plurality of patches. This method for making the patch isdisclosed in U.S. Pat. No. 4,770,731, entitled “Method of Making a Patchfor a Shrinkable Bag”, which is hereby incorporated, in its entirety, byreference thereto.

The patch bag can be provided with just one patch, or with more than onepatch. A bag can have a first patch adhered to a first lay-flat side anda second patch adhered to a second lay-flat side. The patches can be thesame size or of different sizes. For example, one patch can be large andon the first lay-flat side of the bag, and the second patch can be smalland on the second lay-flat side of the bag. One, both, or all of thepatches can be provided patch tear initiators aligned with respectivebag tear initiators.

The bag tear initiator is separated from the patch tear initiator by adistance of at least 0.5 inch. A tear propagation line for a controlleddirection tear extends from bag tear initiator into the patch tearinitiator. The bag tear initiator can be separated from the patch tearinitiator by a distance of at least 1 inch, or at least 1.5 inches, orat least 2 inches, or at least 2.5 inches, or at least 3 inches, or atleast 3.5 inches, or at least 4 inches, or at least 4.5 inches, or atleast 5 inches, or at least 5.5 inches, or at least 6 inches, etc. Thebag tear initiator can be separated from the patch tear initiator by adistance of from 0.5 to 10 inches, or from 0.5 to 6 inches, or from 1 to6 inches, or from 2 to 6 inches, or from 2 to 5 inches.

The patch tear initiator is located along an edge of the patch andpreferably comprises a notch. A “V-shape” notch is preferred because itconcentrates the tear force at the base of the “V.” The included angleof the V can be, for example, an angle within the range of from 5degrees to 150 degrees, or from 10 degrees to 120 degrees, or from 20degrees to 90 degrees, or from 40 to 90 degrees, or from 50 to 80degrees. The depth of the notch can be from 2 mm to 50 mm, or from 3 mmto 25 mm, or from 4 mm to 20 mm, or from 5 mm to 15 mm. The patch tearinitiator can have a V notch in combination with a slit at the base ofthe V-notch, with this combination being referred to as a “Y-notch.” Theedge of the patch can be provided with a plurality of tear initiators sothat if the tear line from the bag tear initiator deviates from an MD orTD line between the bag tear initiator and the patch tear initiator, thedeviating tear line will still propagate into a patch tear initiator sothat the bag and patch will tear together along a tear line to theopposite edge of the patch and to the opposite edge of the bag. Thedistance between the bag tear initiator and the patch tear initiatoraligned therewith can be from 1 inch to 10 inches, or from 1 inch to 5inches, or from 1 inch to 4 inches, or from 1.5 inches to 3.5 inches.

End-seal bags with curved heat seals, and end-seal patch bags withcurved heat seals, can be designed for manual tear initiation and manualdirectional tear propagation. While the end-seal may be curved, thebottom edge of the bag may be straight across the tubing, or may also becurved. A curved bottom heat seal and a straight across bag bottom edgeleaves room at the bottom corners of the bag for providing the tearinitiator, and also for a grip assister to facilitate gripping of thebag for the tearing operation. Patch bags with curved end seals aredisclosed in U.S. Pat. No. 6,270,819, to Wiese, which is herebyincorporated, in its entirety, by reference thereto.

The term “polymer”, as used herein, is inclusive of homopolymer,copolymer, terpolymer, etc. “Copolymer” includes copolymer, terpolymer,etc.

Blends of incompatible polymers in one or more film layers providecontrolled direction tear and enhance the tear initiation, tearpropagation, and linear tear properties of the film, including theability to manually tear down the full length or across the full widthof a package made from a patch bag, i.e., tearing through a heat sealand through the patch and to the opposite edge of the patch and theopposite edge of the bag. For a package made from an end-seal patch bag,the tear can be initiated in the bag bottom skirt, and the tear can bemanually extended for up to the full length of the bag and the fulllength of the patch, i.e., to that portion of the package thatcorresponds with the opposite edge of the bag after the bag is used tomake the package. For a package made from a side-seal patch bag, thetear can be initiated in the bag side skirt, and the tear can bemanually extended across the full width of the package (i.e.,corresponding with the full machine direction dimension of the bag) andacross the entirety of the patch and across the entirety of the bag, forup to the full width of the package, i.e., to that portion of thepackage that corresponds with the opposite edge of the side-seal patchbag after the patch bag is used to make the package.

As used herein, the phrase “incompatible polymer blend” includes (i) ablend of a polymer with a non-polymeric material (e.g., inorganicfiller) in which the polymer is not capable of forming a solution or astable two-phase blend and that tend to separate after mixing, as wellas (ii) a blend of a first polymer with a second polymer in which thetwo polymers are not capable of forming a solution or a stable two-phaseblend and that tend to separate after mixing. As used herein, the phrase“incompatible polymers” refers to two polymers (i.e., a blend of atleast two polymers) that are incapable of forming a solution or even astable two-phase blend, and that tend to separate after being mixed.When blended, incompatible polymers are not miscible with one another,and phase separate into a continuous domain and a discontinuous domainthat may be finely dispersed. The presence of one or more film layerscomprising a blend of incompatible polymers may assist, enhance, or evencause the linear tear property of the multilayer heat-shrinkable filmused to make the heat-shrinkable bag.

In an embodiment, a two-polymer incompatible polymer blend can comprisea 60 to 85 wt % of a first polymer and 15 to 40 wt % of a second polymerwhich is incompatible with the first polymer. In an embodiment, the filmcan comprise the incompatible polymer blend in an amount of from 25 to100 wt %, based on the total weight of the film.

The blend of incompatible polymers can comprise at least one blendselected from the group consisting of:

-   -   (A) a blend of ethylene/α-olefin copolymer with ethylene/vinyl        acetate copolymer (particularly EVA with at least 10 wt. % vinyl        acetate, or at least 15 wt. % vinyl acetate, or at least 20 wt %        vinyl acetate, or at least 25 wt. % vinyl acetate);    -   (B) a blend of ionomer resin with ethylene/vinyl acetate        copolymer, and/or polybutylene, and/or polypropylene        (particularly propylene copolymer);    -   (C) a blend of homogeneous ethylene/α-olefin copolymer with        recycled polymer blend comprising ethylene homopolymer,        propylene homopolymer, ethylene copolymer, propylene copolymer,        polyamide, ethylene/vinyl alcohol copolymer, ionomer resin,        anhydride-modified ethylene/α-olefin copolymer, and/or        antiblock; (D) a blend of ethylene/vinyl acetate copolymer with        polypropylene (particularly propylene/ethylene copolymer),        and/or polybutylene, and/or modified ethylene/vinyl acetate        copolymer, and/or polystyrene (particularly random and/or block        styrene/butadiene copolymer);    -   (E) a blend of ethylene/norbornene copolymer with ethylene/vinyl        acetate copolymer and/or polypropylene and/or polybutylene;    -   (F) a blend of ethylene/α-olefin copolymer with polypropylene        (particularly propylene/ethylene copolymer) and/or polybutylene        and/or ethylene/norbornene;    -   (G) a blend of single site catalyzed polypropylene (i.e.,        homogeneous polypropylene) with homogeneous ethylene/α-olefin        copolymer and/or ethylene/vinyl acetate;    -   (H) a blend of polypropylene and/or ethylene/propylene copolymer        and/or polybutylene with ethylene/methyl acrylate copolymer        and/or ethylene/acrylic acid copolymer and/or ethylene/butyl        acrylate copolymer; and    -   (I) a blend of polyamide with polystyrene and/or        ethylene/α-olefin copolymer and/or ethylene/vinyl acetate        copolymer and/or styrene/butadiene copolymer (random and/or        block copolymer).

The tear initiation, tear propagation, and linear tear property of amultilayer heat-shrinkable film from which the bag is made, and/or thefilm from which the patch is made, may also be enhanced by providing oneor more layers of the film with a filler material, such as an inorganicfiller. Polymeric systems that incorporate high filler concentrationsmay also enhance linear tear behavior. Depending on the particle sizeand dispersion, a filler concentration as low as 5 wt % filler (i.e.,based on total layer weight) in ethylene/α-olefin copolymer,polypropylene, propylene/ethylene copolymer, polybutylene,polystyrene/butadiene copolymer, ionomer resin, ethylene/vinyl acetatecopolymer, ethylene/butyl acrylate copolymer, ethylene/methyl acrylatecopolymer, ethylene/acrylic acid copolymer, polyester, polyamide, etc.,may contribute to the linear tear behavior. More particularly, thepresence of filler in an amount of from 5 to 95 wt %, or in an amount offrom 5 to 50 wt %, or in an amount of from 10 to 40 wt %, or from 20 to35 wt %, may be used.

Suitable fillers include silicates (particularly sodium silicate,potassium silicate, and aluminum silicate, alkali alumino silicate),silica (particularly amorphous silica), siloxane, silicone resin, zincsulfide, wollastonite, microspheres, glass fiber, metal oxide(particularly oxides of titanium, zinc, antimony, magnesium, iron, andaluminum), calcium carbonate, sulfate (particularly barium sulfate andcalcium sulfate), aluminum trihydrate, feldspar, perlite, gypsum, iron,fluoropolymer, crosslinked polymethylmethacrylate, talc, diatomaceousearth, zeolites, mica, kaolin, carbon black, and graphite.

The filler concentration required to achieve low tear initiation forceis dependent on particle geometry, particle size, particle aspect ratio,and compatibility of the filler and the polymer matrix. Some fillers arechemically treated to improve the compatibility of the particle and thepolymer into which it is dispersed.

The tear initiation, tear propagation, and linear tear property of amultilayer heat-shrinkable film may also be enhanced by providing one ormore layers of the film with a polymer that provides the film with arelatively high Young's modulus, e.g., a polymer having a Young'smodulus of at least 80,000 psi. Such polymers can comprise at least onemember selected from the group consisting of high density polyethylene,ultra high molecular weight polyethylene, polypropylene (particularlypropylene homopolymer), styrene copolymer (particularlystyrene/butadiene block copolymer), ethylene/norbornene copolymer,semi-crystalline polyamide, amorphous polyamide (including polyamide6I/6 T), polycarbonate, and polyester. The multilayer heat-shrinkablefilm may have a Young's Modulus of at least 80,000 psi. Young's modulusmay be measured in accordance with one or more of the following ASTMprocedures: D638, D882; D5026-95a; D4065-89, each of which isincorporated herein in its entirety by reference. The film may have aYoung's modulus of at least about, and/or at most about, any of thefollowing: 100,000; 130,000; 150,000; 200,000; 250,000; 300,000;350,000; and 400,000 pounds/square inch, measured at a temperature of73° F. The film may have any of the forgoing ranges of Young's modulusin at least one direction (e.g., in the machine direction or in thetransverse direction) or in both directions (i.e., the machine (i.e.,longitudinal) and the transverse directions).

As used herein, terms such as “polyamide”, “polyolefin”, “polyester”,etc are inclusive of homopolymers of the genus, copolymers of the genus,terpolymers of the genus, etc, as well as graft polymers of the genusand substituted polymers of the genus (e.g., polymers of the genushaving substituent groups thereon).

As used herein, the phrase “propylene/ethylene copolymer” refers to acopolymer of propylene and ethylene wherein the propylene mer content isgreater than the ethylene mer content. Propylene/ethylene copolymer isnot a species of “ethylene/α-olefin copolymer”.

The phrase “ethylene/α-olefin copolymer” is particularly directed toheterogeneous copolymers such as linear low density polyethylene(LLDPE), very low and ultra low density polyethylene (VLDPE and ULDPE),as well as homogeneous polymers such as metallocene catalyzed polymerssuch as EXACT® resins obtainable from the Exxon Chemical Company, andTAFMER® resins obtainable from the Mitsui Petrochemical Corporation. Allthese latter copolymers include copolymers of ethylene with one or morecomonomers selected from C₄ to C₁₀ α-olefin such as butene-1 (i.e.,1-butene), hexene-1, octene-1, etc. in which the molecules of thecopolymers comprise long chains with relatively few side chain branchesor cross-linked structures. This molecular structure is to be contrastedwith conventional low or medium density polyethylenes which are morehighly branched than their respective counterparts. The heterogeneousethylene/α-olefins commonly known as LLDPE have a density usually in therange of from about 0.91 grams per cubic centimeter to about 0.94 gramsper cubic centimeter. Other ethylene/α-olefin copolymers, such as thelong chain branched homogeneous ethylene/α-olefin copolymers availablefrom the Dow Chemical Company, known as AFFINITY® resins, are alsoincluded as another type of homogeneous ethylene/α-olefin copolymeruseful in the film and process described herein.

The film from which the bag is made is a multilayer heat-shrinkablefilm. The patch also comprises a heat-shrinkable film. Heat-shrinkablefilms can be produced monoaxial or biaxial orientation. As used herein,the phrase “heat-shrinkable” is used with reference to films whichexhibit a total free shrink (i.e., the sum of the free shrink in boththe machine and transverse directions) of at least 10% at 185° F., asmeasured by ASTM D 2732, which is hereby incorporated, in its entirety,by reference thereto. All films exhibiting a total free shrink of lessthan 10% at 185° F. are herein designated as being non-heat-shrinkable.The heat-shrinkable film multilayer film from which the bag is made, andthe heat-shrinkable film from which the patch is made, can have a totalfree shrink at 185° F. of from 10 percent to 150 percent, or from 15percent to 120 percent, or from 20 percent to 100 percent, or from 30percent to 80 percent, or from 35 percent to 60 percent, as measured byASTM D 2732.

Heat shrinkability is achieved by carrying out orientation in the solidstate (i.e., at a temperature below the glass transition temperature ofthe polymer). The total orientation factor employed (i.e., stretching inthe transverse direction and drawing in the machine direction) can beany desired factor, such as at least 2×, at least 3×, at least 4×, atleast 5×, at least 6×, at least 7×, at least 8×, at least 9×, at least10×, at least 16×, or from 1.5× to 20×, from 2× to 16×, from 3× to 12×,or from 4× to 9×.

In the multilayer, heat-shrinkable film, all of the film layers can bearranged symmetrically with respect to the polymeric composition of eachfilm layer. In addition, all of the film layers can be arrangedsymmetrically with respect to both composition and thickness. In oneembodiment, the seal layer is thicker than the second outer layer. Theseal layer can have a thickness of from 110% to 300% of the thickness ofthe second outer layer, or from 150% to 250% of the thickness of thesecond outer layer.

FIG. 1 and FIG. 2 together illustrate a schematic of end-seal patch bag10, in a lay-flat position. End-seal patch bag 10 is made from aseamless film tubing, with the machine direction running from open topedge 14 to bottom edge 20. Viewing FIGS. 1 and 2 together, end-sealpatch bag 10 comprises bag 12 made from a multilayer heat-shrinkablefilm, with bag top edge 14 defining an open top, folded first side edge16, folded second side edge 18, bottom edge 20, and end seal 22 runningin the transverse direction. Bag 12 has first lay-flat side 24 andsecond lay-flat side 26. Adhered to bag 12 is patch 28. Bag 12 furthercomprises skirt 30 outward of end seal 22, i.e., “outward” in that bagskirt 30 is exterior of the product-containing cavity within patch bag10. Bag skirt 30 extends all the way around the bottom of bag 12, andcan be considered as first bag skirt on first lay-flat side 28 andsecond bag skirt on second lay-flat side 26. Bag skirt 30 has first tearinitiator 32 on first lay-flat side 24, second tear-initiator 34 insecond lay-flat side 26. Patch 28 has Y-shaped patch tear initiator 36.Patch tear initiator 36 is positioned along a machine direction tearline extending from first tear initiator 32. Skirt 30 also containsfirst grip assister 38 and second grip assister 40, each of which passthrough both first lay-flat side 24 and second lay-flat side 26 of skirt30. Thus, first grip assister 38 in FIG. 1 is actually a pair of gripassisters, i.e., one in first lay-flat side 24 and another directlybeneath, in lay-flat side 26. In the same manner, second grip assister40 is also a pair of grip assisters. First grip assister 38 has hangingchads 42 therein, and second grip assister has hanging chads 44 therein.

Skirt 30 also contains supplemental heat seal 46 of first lay-flat side12 to second lay-flat side 26, which serves to enhance useraccessibility to tear initiators 32 and 34 as well as grip assisters 38and 40. Supplemental heat seal 46 anneals and/or heatsets a portion ofskirt 30, thereby reducing curling and shrinking of skirt 30 during theshrinking of bag 12 around the bone-in meat product sealed inside of bag12. Reduced curling and reduced shrinking of skirt 30 enhances end userdetection and utilization of tear initiators 32 and 34, as well as gripassisters 38 and 40. The absence of supplemental seal 46 results in moreshrinking a curling of skirt 30 during the heat shrinking of patch bag10 around the meat product, making skirt 30 more difficult to detect anduse for opening the package made from patch bag 10.

Patch bag 10 can be used to prepare a packaged product, by placing aproduct inside patch bag 10, evacuating the atmosphere from within patchbag 10, sealing the bag closed, and shrinking bag 12 and patch 28 aroundthe product inside bag 12. Thereafter, now shrunken bag 12 can bemanually opened without the use of a knife or scissors, by initiatingmanual tears from first tear initiator 32 and second tear initiator 34.The design of the multilayer film from which bag 12 is made is such thatupon grasping shrunken bag 12 in the skirt region on each side of tearinitiators 32 and 34, as a first tear is initiated and propagated fromfirst tear initiator 32, the tear direction is controlled so that thetear naturally travels up first lay-flat side 24 in the machinedirection, along a line intersecting now shrunken patch 28 at patch tearinitiator 36. Once the tear line meets patch tear initiator 36, thecontinued exertion of the tearing force causes patch 28 to tear in themachine direction together along the same tear line as the furthertearing of bag 12. The adhesion of patch 28 to bag 12 causes furthertearing in the machine direction by both shrunken bag 12 and shrunkenpatch 28. Moreover, the tearing in the machine direction is a tear fromthe bottom edge 20 of bag 12, all the way to top edge 14 of patch bag10, including tearing of patch 28 from tear initiator 36 through toopposite edge 48 of patch 28.

Patch tear initiator 36 is important to achieving machine direction tearof shrunken bag 12 and shrunken patch 28. Without the presence of patchtear initiator 36, a machine direction tear is not initiated andpropagated in shrunken patch 28. Rather, without patch tear initiator 36a machine direction tear propagating up shrunken bag 12, if continuedonward after the tear meets the edge of patch 28, will continue throughbag 12 but will cause shrunken patch 28 to delaminate from bag 12 ratherthan tear. Without patch tear initiator 36, a large manual force isrequired to both delaminate shrunken patch 28 from shrunken bag 12 inorder to continue the machine direction tear of shrunken bag 12 to openthe package. The presence of patch tear initiator 36 allows force to beconcentrated on patch 28 at patch tear initiator 36, resulting in thesimultaneous tearing of both bag 12 and patch 28, with patch 28 tearingthrough to opposite edge 48 and bag 12 tearing through to opposite edge14.

FIG. 3 and FIG. 4 together illustrate a schematic of heat-shrinkableside-seal patch bag 50, in a lay-flat position. Side-seal patch bag 50is made from a single piece of film, with the film having machinedirection of film manufacture running from first side edge 58 to secondside edge 60, and with the transverse direction of film manufacturerunning from top edge 54 of the open top, to folded bottom edge 56.Side-seal patch bag 50 comprises bag 52 made from a multilayerheat-shrinkable film, with bag 52 having first lay-flat side 66, secondlay-flat side 68, bag top edge 54 defining an open top, folded bottomedge 56, first side edge 58, second side edge 60, first side seal 62,second side seal 64. Bag 52 further comprises first skirt 82 outward offirst side seal 62. First bag skirt 82 extends all the way around thebottom of bag 12, and can be considered as including both that portionof the skirt on first lay-flat side 66 as well as the portion of theskirt on second lay-flat side 68. First bag skirt 82 has first tearinitiator 70 on first lay-flat side 66, and second tear-initiator 72 onsecond lay-flat side 68. Patch 86 has Y-shaped patch tear initiator 88.Patch tear initiator 88 is positioned along a machine direction tearline extending from first tear initiator 70, so that a tear initiatedand propagated from tear initiator 70 propagated to patch tear initiator88, with further tearing resulting in the tear in bag 52 propagating tosecond side edge 60 while concurrently a tear is propagated across patch86 from tear initiator 88 to opposite patch edge 90. First skirt 82 alsocontains first grip assisters 74 and second grip assisters 78, each ofwhich pass through both first lay-flat side 66 and second lay-flat side68 of skirt 82. First grip assisters 74 have respective hanging chads 76therein, and second grip assisters 78 have respective hanging chads 44therein. First skirt 82 also contains supplemental heat seal 92 outwardof tear initiators 70 and 72 and parallel to first side edge 58.Supplemental heat seal 92 is a heat seal of the first lay-flat side ofskirt 82 to the second lay-flat side of skirt 58. Supplemental heat seal92 reduces curling and shrinking of skirt 82, thereby enhancing end userdetection and utilization of tear initiators 70 and 72, as well as gripassisters 74 and 78.

FIG. 5 illustrates a schematic of heat-shrinkable pouch-style patch bag100, in lay-flat position. Pouch-style patch bag 100 is made from twopieces of film, with each piece of film having machine direction of filmmanufacture running from top edge 102 to bottom edge 104. Pouch-stylepatch bag 100 comprises heat shrinkable pouch 106 made from two piecesof a multilayer heat-shrinkable film, with pouch 106 having firstlay-flat side 108, second lay-flat side 110, top edge 102, bottom edge104, first side edge 112, second side edge 114, first side seal 116 (aheat seal), second side seal 118 (a heat seal), bottom seal 120 (a heatseal), first side skirt 122, second side skirt 124, bottom skirt 126,first tear initiator 128 in first lay-flat side 108, second tearinitiator 130 in second lay-flat side 110, first grip assisters 132having hanging chads 134, second grip assisters 136 having hanging chads138, and supplemental heat seal 140. Patch 142 is adhered to pouch 106,with patch 142 having Y-shaped patch tear initiator 144 on a first edge,with patch tear initiator 144 aligned with first tear initiator 128 forthe propagation of a controlled direction tear through patch 142 toopposite patch edge 146. First side skirt 122 includes two discreteskirts joined at first side seal 116, i.e., the side skirt outward offirst side seal 116 on first lay-flat side 108, as well as the sideskirt outward of heat seal 116 on second lay-flat side 110. Second sideskirt 124 includes two discrete skirts joined at heat seal 118, i.e.,the skirt outward of heat seal 118 on first lay-flat side 108, as wellas the skirt outward of heat seal 118 on second lay-flat side 110.Bottom skirt 126 has first tear initiator 128 on first lay-flat side108, and second tear-initiator 130 on second lay-flat side 110. Patch142 has Y-shaped patch tear initiator 144. Patch tear initiator 144 ispositioned along a machine direction tear line extending from first tearinitiator 128, so that a tear initiated and propagated from tearinitiator 128 can be propagated to patch tear initiator 144, withfurther tearing resulting in the tear in pouch 106 propagating to secondopposite edge 102 while concurrently a tear is propagated up patch 142from patch tear initiator 144 to opposite patch edge 146. Bottom skirt126 also contains first grip assisters 132 and second grip assisters136, each of which pass through both first lay-flat side 108 and secondlay-flat side 110 of skirt 126. First grip assisters 132 have respectivehanging chads 134 therein, and second grip assisters 136 have respectivehanging chads 138 therein. Bottom skirt 126 also contains supplementalheat seal 140 outward of tear initiators 132 and 136 and parallel tobottom edge 104. Supplemental heat seal 140 is a heat seal of the firstlay-flat side of bottom skirt 126 to the second lay-flat side of bottomskirt 126. Supplemental heat seal 140 reduces curling and shrinking ofskirt 126, thereby enhancing end user detection and utilization of tearinitiators 128 and 130, as well as grip assisters 132 and 136.

FIGS. 6A and 6B together illustrate a schematic of backseamed patch bag350 in lay-flat position, with FIG. 6B being a cross-sectional viewthrough section 6B-6B of FIG. 6A. Backseamed patch bag 350 comprises bag351 made from a single piece of multilayer film 374, with the film 374having machine direction running from top edge 352 to bottom edge 354.Bag 351 has first lay-flat side 356, second lay-flat side 358, firstfolded side edge 360, second folded side edge 362, transverse bottomheat seal 364, bottom skirt 366 between bottom heat seal 364 and bottomedge 354, and lengthwise backseam fin-type heat seal 368 in secondlay-flat side 358. Outward of fin heat seal 368 are fin tails 370 havingfin edges 372. Bottom skirt 366 has first slit-type tear initiator 376in first lay-flat side 356, and second slit-type tear-initiator 378 insecond lay-flat side 358. Bag 351 has patch 380 adhered to firstlay-flat side 356, with patch 380 having Y-shaped notch+slit type patchtear initiator 382 aligned with a machine direction tear line emanatingfrom first tear initiator 376, so that the tear initiated and propagatedfrom first tear initiator 376 propagates into patch tear initiator 88,with further tearing resulting in the further tearing of bag 351together with patch 380 from tear initiator 382 to opposite patch edge384, and thereafter onward toward top edge 352 of bag 351. Skirt 366also contains first grip assisters 384 and second grip assisters 386,each of which pass through both first lay-flat side 356 (as illustrated)and second lay-flat side 358 (not illustrated) of skirt 366. First gripassisters 384 have respective hanging chads 388 therein, and second gripassisters 386 have respective hanging chads 390 therein. Skirt 366 alsocontains supplemental heat seal 392 outward of tear initiators 376 and378 and parallel to first bottom edge 354. Supplemental heat seal 392 isa heat seal of the first lay-flat side of skirt 366 to the secondlay-flat side of skirt 366. Supplemental heat seal 392 reduces curlingand shrinking of skirt 366 in the region of tear initiators 376 and 378as well as in the region of grip assisters 384 and 386, therebyenhancing end user detection and utilization of the tear initiators andgrip assisters for the easy manual tearing open of bag 351 and patch380. Although FIGS. 6A and 6B illustrate a backseamed patch bag with afin-type backseam heat seal, alternatively the backseam heat seal couldbe a lap-type backseam heat seal in which the inside layer of the bagfilm is heat sealed to the outside layer of the bag film.

FIG. 7 illustrates a schematic of alternative heat-shrinkable end-sealpatch bag 150, in lay-flat position. Alternative patch bag 150 largelycorresponds with end-seal heat-shrinkable patch bag 10 of FIG. 1. Patchbag 150 has bag 151 having first lay-flat side 152, second lay-flat side154, top edge 156, bottom edge 158, first side edge 160, second sideedge 162, end seal 164 (a heat seal), skirt 166, first tear initiator168 in first lay-flat side 152, second tear initiator 170 in secondlay-flat side 154, first grip assisters 172 having hanging chads 174,second grip assisters 176 having hanging chads 178, and foursupplemental spot seals 180. Patch 182 is adhered to bag 151, with patch182 having bottom edge 184 with patch tear initiators 186, 188, and 190adjacent one another. Middle patch tear initiator 188 is Y-shaped and ispositioned along an MD tear line from first tear initiator 168. However,in the event that a tear propagating from first tear initiator 168deviates slightly from the machine direction, it will likely propagateinto either Y-shaped patch tear initiator 186 or V-shaped patch tearinitiator 190. The multiplicity of patch tear initiators in patch bag150 reduces the need for precision in aligning a single patch tearinitiator with the bag tear initiator. In fact, the entire lower edge ofthe patch can be provided with tear initiators so that the tearpropagated from the bag tear initiator will undoubtedly propagate into apatch tear initiator in the edge of the patch closest to the bag tearinitiator. The patch tear initiators can have a Y-shape, V-shape,U-shape, etc. Each of Y-shape of patch tear initiators 186 and 188provides an enhanced point of stress concentration in providing a cutwhich is along the desired line of tear propagation to the opposite edge192 of patch 182. However, the V-shape of patch tear initiator 190 hasalso been found to provide enough stress concentration to enable a tearto initiate and propagate from patch tear initiator 190 to opposite edge192 of patch 182. Of course, the embodiments of FIG. 1, FIG. 3 and FIG.5 could also have a V-shaped patch tear initiator instead of the Y-shapepatch tear initiators illustrated in FIG. 1, FIG. 3, and FIG. 5. Otherpatch tear initiator shapes are also operable, such as a straight slit,a curved slit, a semicircular notch, a square-shaped notch, arectangle-shaped notch, a half pentagon shaped notch, a half hexagonshaped notch, a half oval shaped notch, etc.

The four spot welds 180 in FIG. 7 are an alternative to the supplementalseal 46 of the embodiment of FIG. 1, the supplemental seal 92 of theembodiment of FIG. 3, and the supplemental seal 140 of the embodiment ofFIG. 5. As with supplemental seals 46, 92, and 140, spot welds 180 areheat seals of the first lay-flat side of skirt 166 to the secondlay-flat side of skirt 166. As with supplemental seals 46, 92, and 140,spot welds 180 enhance end user detection and utilization of tearinitiators 168 and 170, as well as grip assisters 172 and 176, byannealing/heat-setting a portion of skirt 166 to reduce shrinkage andcurling upon shrinking the film against the meat product inside the bag.

FIG. 8 is a perspective view of the front of packaged product 300containing a bone-in meat product 302 having a protruding bone end 304,with meat product 302 being completely surrounded by packaging article306, which has been shrunk tightly around meat product 302. Packagingarticle 306 was prepared from a heat-shrinkable end-seal patch bagcomprising a heat-shrinkable bag (made from heat shrinkable film 308)into which meat product 302 was placed, with meat product 302 positionedwithin the bag so that the heat-shrinkable patch 310 on the bag coveredprotruding bone end 304. Atmosphere within the heat-shrinkable bag wasthen evacuated and the open end of the bag sealed closed at top heatseal 324. The heat-shrinkable bag film and heat-shrinkable patch filmwere then shrunk tightly around meat product 302 by passing the packagedproduct through a hot air shrink tunnel, resulting in packaged product300 as illustrated in FIG. 8.

Packaged product 300 has bottom skirt 312 bounded by bottom edge 314,side edges 315 and 317, and heat seal 316. Front and back sides of skirt312 have tear initiators 316 & 317, respectively, as well as first pairof grip assisters 318&319, respectively, and 320&321, respectively.Moreover, the front and back sides of skirt 312 are heat sealed togetherat four spot seals 322. Skirt 326 above top heat seal 324 has shrunkenand curled as a result of the shrinking of the heat-shrinkable bag film308. Patch 310 has patch tear initiator 328 aligned with tear initiator317 in skirt 312, so that a controlled direction MD tear from tearinitiator 317 will propagate into patch tear initiator 328, with bagfilm 330 and patch 310 thereafter tearing together in the machinedirection up the length of the packaging article 306 to the oppositeedge 330 of patch 310, and then on to the opposite edge 332 of bag film308.

FIG. 9 illustrates a schematic of a preferred process for producing themultilayer heat-shrinkable film from which the bag can be made. In theprocess illustrated in FIG. 9, solid polymer beads (not illustrated) arefed to a plurality of extruders 200 (for simplicity, only one extruderis illustrated). Inside extruders 200 the polymer beads are forwarded,melted, and degassed, following which the resulting bubble-free melt isforwarded into die head 202, and extruded through an annular die,resulting in tubing 204 which is 10 to 30 mils thick, more preferably 15to 25 mils thick.

After cooling or quenching by water spray from cooling ring 206, tubing204 is collapsed by pinch rolls 208, and is thereafter fed throughirradiation vault 210 surrounded by shielding 209, where tubing 204 isirradiated with high energy electrons (i.e., ionizing radiation) fromiron core transformer accelerator 214. Tubing 204 is guided throughirradiation vault 210 on rolls 212. Preferably, tubing 204 is irradiatedto a level of about 4.5 MR.

After irradiation, irradiated tubing 216 is directed through nip rolls218, following which irradiated tubing 216 is slightly inflated,resulting in trapped bubble 220. However, at trapped bubble 220, thetubing is not significantly drawn longitudinally, as the surface speedof nip rolls 224 are about the same speed as nip rolls 218. Furthermore,irradiated tubing 216 is inflated only enough to provide a substantiallycircular tubing without significant transverse orientation, i.e.,without stretching.

Slightly inflated, irradiated tubing 216 is passed through vacuumchamber 222, and thereafter forwarded through coating die 225. Secondtubular film 226 is melt extruded from coating die 225 and coated ontoslightly inflated, irradiated tube 220, to form two-ply tubular film228. Second tubular film 226 preferably comprises an O₂-barrier layer,which does not pass through the ionizing radiation. Further details ofthe above-described coating step are generally as set forth in U.S. Pat.No. 4,278,738, to BRAX et al, which is hereby incorporated by referencethereto, in its entirety.

After irradiation and coating, two-ply tubing film 228 is wound up ontowindup roll 230. Thereafter, windup roll 230 is removed and installed asunwind roll 232 on a second stage in the process of making the tubingfilm as ultimately desired. Two-ply tubular film 228, from unwind roll232, is unwound and passed over guide roll 234, after which two-plytubular film 228 passes into hot water bath tank 236 containing hotwater 238. The now collapsed, irradiated, coated tubular film 228 issubmersed in hot water 238 (having a temperature of about 210° F.) for aretention time of at least about 5 seconds, i.e., for a time period inorder to bring the film up to the desired temperature for biaxialorientation. Thereafter, irradiated tubular film 228 is directed throughnip rolls 240, and bubble 242 is blown, thereby transversely stretchingtubular film 228. Furthermore, while being blown, i.e., transverselystretched, nip rolls 244 draw tubular film 228 in the longitudinaldirection, as nip rolls 244 have a surface speed higher than the surfacespeed of nip rolls 240. As a result of the transverse stretching andlongitudinal drawing, irradiated, coated biaxially-oriented blown tubingfilm 246 is produced, this blown tubing preferably having been bothstretched in the solid state in a ratio of from about 1:1.5-1:6, anddrawn in a ratio of from about 1:1.5-1:6. More preferably, thestretching and drawing are each performed a ratio of from about 1:2-1:4.The result is a biaxial orientation of from about 1:2.25-1:36, morepreferably, 1:4-1:16. While bubble 242 is maintained between pinch rolls240 and 244, blown tubing film 246 is collapsed by rolls 248, andthereafter conveyed through nip rolls 244 and across guide roll 250, andthen rolled onto wind-up roll 252. Idler roll 254 assures a goodwind-up.

FIG. 10 illustrates a schematic of a preferred process for producing amultilayer film from which the heat-shrinkable patch is made. In theprocess illustrated in FIG. 10, solid polymer beads (not illustrated)are fed to a plurality of extruders 300 (for simplicity, only oneextruder is illustrated). Inside extruders 300, the polymer beads areforwarded, melted, and degassed, following which the resultingbubble-free melt is forwarded into die head 302, and extruded throughannular die, resulting in tubing 304 which is 5-40 mils thick, morepreferably 20-30 mils thick, still more preferably, about 25 mils thick.

After cooling or quenching by water spray from cooling ring 306, tubing304 is collapsed by pinch rolls 308, and is thereafter fed throughirradiation vault 310 surrounded by shielding 312, where tubing 304 isirradiated with high energy electrons (i.e., ionizing radiation) fromiron core transformer accelerator 314. Tubing 304 is guided throughirradiation vault 310 on rolls 316. Preferably, the irradiation oftubing 304 is at a level of about 7 MR.

After irradiation, irradiated tubing 318 is directed over guide roll320, after which irradiated tubing 318 passes into hot water bath tank322 containing water 324. The now collapsed irradiated tubing 318 issubmersed in the hot water for retention time of at least about 5seconds, i.e., for a time period in order to bring the film up to thedesired temperature, following which supplemental heating means (notillustrated) including a plurality of steam rolls around whichirradiated tubing is partially wound, and optional hot air blowers,elevate the temperature of irradiated tubing 318 to a desiredorientation temperature of from about 240° F. to 250° F. Thereafter,irradiated film tubing 318 is directed through nip rolls 326, and bubble328 is blown, thereby transversely stretching irradiated tubing 318.Furthermore, while being blown, i.e., transversely stretched, nip rolls330 draw irradiated film 318 in the longitudinal direction, as nip rolls330 have a higher surface speed than the surface speed of nip rolls 326.As a result of the transverse stretching and longitudinal drawing,irradiated, biaxially-oriented blown tubing film 332 is produced, thisblown tubing preferably having been both stretched in a ratio of fromabout 1:1.5-1:6, and drawn in a ratio of from about 1:1.5-1.6. Morepreferably, the stretching and drawing are each performed a ratio offrom about 1:2-1:4. The result is a biaxial orientation of from about1:2.25-1:36, more preferably, 1:4-1:16. While bubble 328 is maintainedbetween pinch rolls 326 and 330, blown tubing is collapsed by rolls 334and nip rolls 330 to form self-welded tubing 332, which is thereafterconveyed across guide roll 336 and rolled onto wind-up roll 338, viaidler roll 340.

Preferably, the stock film from which the bag is formed has a totalthickness of from about 1.2 to 5 mils, or 1.5 to 4 mils, or 1.6 to 3mils, or 1.7 to 2.5 mils, or 1.8 to 2.2 mils, or about 2 mils.Preferably the stock film from which the bag is formed is a multilayerfilm having from 3 to 12 layers, or 4 to 10 layers, or 5 to 9 layers, or6 to 8 layers.

Grip assist holes can be sized to allow a user's finger(s) to beinserted therethrough to assist in gripping the film. Grip assist holeswork in conjunction with the tear initiators, by providing a securemanual grip of the bag in a location designed to assist in generatingtear initiation force along a tear line emanating from the tearinitiators.

The grip assist hole in a first lay-flat side of the bag can overlap orcoincide with the grip assist hole in a second lay-flat side of the bag.While grip assist holes can have any desired shape (e.g., round,rectangular, square, triangular, pentagonal, hexagonal, etc.),preferably the holes are round, or any “corners” on the holes arerounded, to reduce the presence of stress concentration points thatcould cause a tear to initiate from the grip assist hole, as anobjective is to have the tear initiated from the tear initiator, withthe tear running to an opposite side edge of the bag.

In one embodiment, the grip-assist holes can be made by cutting throughboth lay-flat sides of the bag to remove a piece of film to form theholes. However, this process produces small, loose pieces of filmcorresponding with the size of the cut hole. In order to avoid thepossibility of having these small, loose pieces of film get inside thebag, they must be controlled and collected, which lowers the efficiencyof the production process while at the same time increasing thecomplexity of the production process. It is simpler and more efficientto provide the grip assisters in a shape that corresponds with a“partial hole cut”, i.e., a cut through the film to make a portion ofthe hole, the cut not being complete so that a hole is formed, asillustrated in FIGS. 1, 3, 4, 5, 6A, and 7. Such partial cuts leave a“hanging chad” so that no separated small pieces of film are produced.

Resins Utilized in the Examples

Unless otherwise indicated, the following listing of resins identifiesthe various resins utilized in the Example below.

TABLE 1 Generic Resin Name Melt Resin {additional Density Index codeTradename information} (g/cc) (dg/min) Supplier SSPE 1 Affinity^( ®) PLHomogeneous 0.900 g/cc 6.0 Dow 1281G1 ethylene/octene copolymer SSPE 2Affinity^( ®) PL Homogeneous 0.902 3.0 Dow 1850G ethylene/octenecopolymer VLDPE XUS Very low density 0.903 0.5 Dow 61520.15Lpolyethylene LLDPE 1 Dowlex ® Linear Low Density 0.920 1.0 Dow 2045.03Polyethylene LLDPE 2 LL 3003.32 Heterogeneous 0.9175 3.2 ExxonEthylene/hexene Mobil copolymer EVA 1 Escorene^( ®) Ethylene/vinyl 0.9333.5 Exxon LD 713.93 acetate Mobil copolymer (14.4% V A) EVA 2Escorene^( ®) Ethylene/vinyl 0.950  5.75 Exxon LD 761.36 acetate Mobilcopolymer (26.7% VA) EAA Primacor 1410 Ethylene/acrylic 0.938 1.5 Dowadhesive acid copolymer polymer (9.5% acrylic acid) PVDC Saran^( ®) 806Vinylidene chloride/ 1.69 — Dow methyl acrylate copolymer BrightL-7106-AB Optical brightener 0.945 4.5 Bayshore in LDPE Industrial Inc.

Example 1 Working

An end-seal bag was made from a coextruded, multilayer, heat-shrinkablefilm produced utilizing the process set forth in FIG. 9, describedabove. The multilayer film had a total of seven layers, with Layer 1being the inside seal layer and Layer 7 being the outside layer of thetubing and bag, as set forth in Table 2, below.

TABLE 2 Example 1: Multilayer Heat-Shrinkable Bag Film Layer 1 Layer 2Layer 6 Layer 7 80% 70% 70% 80% SSPE1 VLDPE Layer 3 Layer 5 VLDPE SSPE 220% 30% 100% Layer 4 100% 30% 15% LLDPE 2 EVA 1 EVA 1 PVDC EVA 2 EVA 1LLDPE 1 0.43 mil 0.78 mil 0.09 mil 0.18 mil 0.09 mil 0.26 mil 0.17 mils

In the production of this multilayer film, the extrusion-coated tubingwas immersed in 88° C. water for 16 seconds and thereafter oriented by afactor of 4.1 in the machine direction and by a factor of 2.9 in thetransverse direction to produce the heat shrinkable film having a totalthickness of 2 mils. The multilayer film exhibited a total free shrinkat 185° F. of 77%, i.e., 32% in the machine direction and 45% in thetransverse direction. The film exhibited a Peak Load Impact Strength,determined using ASTM D 3763-95A, of 196 Newtons, i.e., 98 Newtons permil of film thickness.

A coextruded, multilayer, heat-shrinkable, self-welded film was producedutilizing the process set forth in FIG. 10, described above, for use asa patch to be adhered to the end-seal bag made from the film of Table 2,described above. The multilayer, heat-shrinkable, self-welded filmtubing for use as a patch was extruded from an annular die as a threelayer extrudate, with Layer 1 being the outside of the tubing and Layer3 being the inside (self-welding) layer of the tubing. The compositionand thickness of the three layers is as set forth in Table 3.

TABLE 3 Multilayer Heat-Shrinkable Patch Film Layer No. Layer 1 Layer 2Layer 3 Layer 90% VLDPE 100% VLDPE 80% EAA Composition 10% Bright Layerthickness 0.43 mil 1.58 mils 0.24 mil Before self-welding Total layerthickness 0.86 mil 3.16 mils 0.48 mil after self welding

Upon self-welding, the three-layer 1/2/3 extrudate of Table 3 formed asix-layer coextruded heat-shrinkable film of the structure 1/2/3/3/2/1,with Layer 1 forming the outer layers of the self-welded heat-shrinkablepatch film and Layer 3 forming the self-welding layer, with the finalthickness of the self welded heat-shrinkable film being 4.5 mils.

The film of Table 2 was seamless tubing having a lay-flat width of 9 to10 inches. The tubing was cut and sealed to form an end-seal bag havinga length of about 17 to 18 inches before shrinking. A patch according toTable 2 was cut and adhered to the outside surface of the bag, resultingin a patch bag in accordance with FIG. 1 and FIG. 2, i.e., with a curvedheat seal and with the patch not extending to the heat seal. The bag wasprovided with the tear initiators, grip assisters, and supplemental heatseal as illustrated in FIG. 1. The patch was provided with a patch tearinitiator as illustrated in FIG. 2, with a machine direction lineextending from a bag tear initiator into the patch tear initiator. Thedistance between the bag tear initiator and the patch tear initiator wasabout 3 inches.

A whole turkey product was placed inside the bag and the atmosphereevacuated from the bag, and the bag sealed closed with a heat seal ofthe inside layer of the bag to itself in a region between the productand the top edge of the bag. The excess bag length was trimmed off andthe resulting package was then shrunk tightly against the product bypassing the packaged product through a shrink tunnel. The packagedproduct was then placed in a refrigerator and cooled to about 2° C. Thecooled packaged product was then removed from the refrigerator and tornopen using two hands, each with a finger through a grip assister. Tearswere manually initiated and manually propagated from each of the twotear initiators in the bag skirt by pulling the grip assisters away fromone another, causing the bag tear initiators to spread open followed byinitiating two machine direction tears, one from each of the two bagtear initiators. The two tears propagated down the length of theshrunken package. One of the MD tears propagated into the patch tearinitiator, and thereafter the patch and bag tore together to theopposite edge of the patch, and as tearing continued, to the oppositeedge of the bag.

Example 2 Comparative

A heat-shrinkable end-seal bag was made as in Example 1, and a patch wasadhered to the bag as in Example 1, except that the patch was notprovided with a tear initiator. Upon insertion of bone-in meat productinto the resulting patch bag, evacuation of atmosphere from the bag,sealing the bag closed, cutting excess bag tail off, shrinking the bagagainst the meat product by passing the packaged product through ashrink tunnel, refrigerating the packaged product, removal and tearingthe bag open using the grip assisters, the result was that the bagexhibited a controlled direction MD tear until the bag tear propagatedto the edge of the patch. Once the bag tear propagated to the edge ofthe patch, the application of further tearing force resulted in aninitial stretching of the patch as the bag continued tearing toward andto the opposite edge of the bag. As the bag tore, the patch delaminatedfully from the bag along one side of the bag MD tear line, anddelaminated partially from the bag on the other side of the bag MD tearline. At no point did the bag and patch tear together. Significantlymore force was required to stretch and delaminate the patch from the bagthan to tear the bag and patch together as in Example 1.

What is claimed is:
 1. A patch bag comprising a heat-shrinkable patchadhered to a heat-shrinkable bag having an open top and a top edge, aclosed bottom and a bottom edge, a first side edge, a second side edge,a first lay-flat side, a second lay-flat side, a heat seal of a regionof the first lay-flat side to a region of the second lay-flat side, afirst tear initiator in the first lay-flat side in a bag skirt outwardof the heat seal or in a bag header between the patch and the top edgeof the bag, a second tear initiator in the second lay-flat side in thebag skirt outward of the heat seal or in the bag header between thepatch and the top edge of the bag, with at least a portion of theheat-shrinkable patch being adhered to an outside surface of the firstlay-flat side of the bag, with the patch having a patch tear initiatorlocated on an edge of the patch in a location separated from the firsttear initiator, the patch tear initiator being aligned with an MD or TDtear line extending from the first bag tear initiator, with the heatshrinkable bag comprising a multilayer film having at least one layercomprising an incompatible polymer blend.
 2. The patch bag according toclaim 1, wherein the incompatible polymer blend comprises at least onemember selected from the group consisting of: (A) a blend of from 80 to60 wt % ethylene homopolymer and/or ethylene/α-olefin copolymer withfrom 20 to 40 wt ethylene/unsaturated ester copolymer having anunsaturated ester content of at least 10 wt %; (B) a blend of ionomerresin with ethylene/unsaturated ester copolymer, and/or polybutylene,and/or propylene homopolymer and/or propylene copolymer; (C) a blend ofhomogeneous ethylene/α-olefin copolymer with recycled polymer blendcomprising ethylene homopolymer, propylene homopolymer, ethylenecopolymer, propylene copolymer, polyamide, ethylene/vinyl alcoholcopolymer, ionomer resin, anhydride-modified ethylene/α-olefincopolymer, and/or antiblock; (D) a blend of from 10 to 75 wt %ethylene/unsaturated ester copolymer with from 90 to 15 wt %polypropylene and/or propylene/ethylene copolymer, and/or polybutylene,and/or modified ethylene/α-olefin copolymer, and/or styrene homopolymer,and/or styrene/butadiene copolymer; (E) a blend of ethylene/norbornenecopolymer with ethylene/unsaturated ester copolymer and/or polypropyleneand/or polybutylene; (F) a blend of from 90 to 15 wt % ethylene/α-olefincopolymer with from 10 to 75 wt % polypropylene and/or polybutyleneand/or ethylene/norbornene; (G) a blend of from 90 to 25 wt %homogeneous propylene homopolymer and/or homogeneous propylene copolymerwith from 10 to 75 wt % homogeneous ethylene/α-olefin copolymer and/orethylene/unsaturated ester copolymer; (H) a blend of propylenehomopolymer and/or propylene/ethylene copolymer and/or polybutylene withethylene/methyl acrylate copolymer and/or ethylene/acrylic acidcopolymer and/or ethylene/butyl acrylate copolymer; (I) a blend ofpolyamide with polystyrene and/or ethylene/α-olefin copolymer and/orethylene/vinyl acetate copolymer and/or styrene/butadiene copolymer; (J)a blend of polyamide 6 and polyamide 6I6T; (K) a blend of athermoplastic polymer and a filler, wherein the filler is present in anamount of at least 5 wt %, based on layer weight.
 3. The heat-shrinkablepatch bag according to claim 1, wherein the bag is an end-seal bagcomprising a seamless tubing with the first and second bag side edgesbeing folded edges, with the heat seal being an end seal across a bottomof the bag, with the skirt being outward of the end seal, with the patchtear initiator being aligned with the MD tear line extending from thefirst tear initiator.
 4. The heat-shrinkable patch bag according toclaim 1, wherein the bag is a side-seal bag having an open top, a foldedbottom edge, first side seal along the first side edge, second side sealalong the second side edge, with respective first and second bag skirtsoutward of respective first and second side seals, with the first andsecond tear initiators being in the first bag skirt and outward of thefirst side seal, with the patch tear initiator being aligned with the MDtear line extending from the first tear initiator.
 5. Theheat-shrinkable patch bag according to claim 1, wherein the bag is apouch having a bottom seal which is a heat seal of the first lay-flatside to the second lay-flat side along the bottom edge, with a bottomskirt between the bottom edge and the bottom seal, and a first side sealwhich is a heat seal of the first lay-flat side to the second lay-flatside along the first side edge with a first side skirt between the firstside seal and the first side edge, a second side seal which is a heatseal of the first lay-flat side to the second lay-flat side along thesecond side edge with a second side skirt between the second side sealand the second side edge, with the first and second tear initiatorsbeing in the same skirt.
 6. The heat-shrinkable patch bag according toclaim 1, wherein the bag is a backseamed bag having a bottom seal whichis a heat seal of the first lay-flat side to the second lay-flat sidealong the bottom edge, with a bottom skirt between the bottom edge andthe bottom seal, with the backseamed bag having a backseamed seal whichis a heat seal of the multilayer film to itself, with the backseam sealbeing on the second lay-flat side of the bag and the backseam runningfrom the bottom edge of the bag to the top edge of the bag.
 7. Theheat-shrinkable patch bag according to claim 1, wherein the patchcomprises a plurality of tear initiators, with one of the tearinitiators being aligned with an MD or TD tear line extending from thefirst bag tear initiator.
 8. The heat-shrinkable patch bag according toclaim 1, wherein the patch tear initiator is V-shaped or Y-shaped. 9.The heat-shrinkable patch bag according to claim 1, wherein the bag filmis a multilayer film comprising an outer seal and meat contact layerwhich is an inside layer of the bag and which comprisesethylene/α-olefin copolymer, an outer abuse layer which is an outsidelayer of the bag and which comprises ethylene/α-olefin copolymer, aninternal O₂-barrier layer, a first tie layer between the seal layer andthe O₂-barrier layer, a second tie layer between the O₂-barrier layerand the abuse layer, a first incompatible polymer blend layer betweenthe seal layer and the first tie layer, and a second incompatiblepolymer blend layer between the abuse layer and the second tie layer,wherein first and second incompatible polymer blend layers comprise ablend of from 60 to 80 wt % ethylene/α-olefin copolymer and 40 to 20 wt% ethylene/unsaturated ester copolymer having an unsaturated estercontent of at least 10 wt %, based on polymer weight, with the amount ofincompatible polymer blend in the film being from 30 to 70 wt %, basedon total film weight, and the patch comprises self-welded multilayerfilm having an outer layer comprising ethylene/α-olefin copolymer,self-weld layer comprising an ethylene unsaturated ester orethylene/unsaturated acid copolymer, and an intermediate layer betweenthe self weld layer and the outer layer comprising ethylene/α-olefincopolymer.
 10. The heat-shrinkable patch bag according to claim 1,wherein the patch is positioned inward of the heat seal and does notextend to the heat seal.
 11. The heat-shrinkable patch bag according toclaim 1, wherein the first tear initiator is placed in a central regionof the bag, and the second tear initiator is placed in the centralregion of the bag, with the central region extending up to 70% of a bagdimension transverse to a centerline.
 12. The heat-shrinkable patch bagaccording to claim 1, wherein the skirt further comprises a gripassister, and at least a portion of the skirt or header is heatset inorder to reduce the shrinkage of the skirt or header upon shrinking thefilm around the product.
 13. The heat-shrinkable patch bag according toclaim 12, wherein the heatset portion is in the skirt and the heatsetportion comprises at least one supplemental heat seal of at least aportion of the first lay-flat side of the skirt to a portion of thesecond lay-flat second side of the skirt.
 14. The heat-shrinkable patchbag according to claim 1, wherein the patch covers at least a portion ofthe heat seal and a portion of the patch covers a portion of the skirt,with the portion of the patch covering the skirt having an edge insidean outer edge of the skirt.
 15. The heat-shrinkable patch bag accordingto claim 1, wherein the multilayer film has Peak Load Impact Strength,determined using ASTM D 3763-95A, of at least 50 Newtons per mil, andthe multilayer film has thickness of from 1.5 to 5 mils.
 16. Theheat-shrinkable patch bag according to claim 1, wherein the patch doesnot have a line of weakness aligned with the patch tear initiator. 17.The patch bag according to claim 1, wherein the first tear initiator andthe second tear initiator are coincident or substantially coincident.18. The heat-shrinkable patch bag according to claim 1, wherein thepatch comprises a heat shrinkable film that does not comprise anincompatible polymer blend.
 19. The heat-shrinkable patch bag accordingto claim 1, wherein the patch comprises a heat shrinkable filmcontaining an incompatible polymer blend.
 20. The heat-shrinkable patchbag according to claim 1, wherein the patch is a first patch adhered toa first lay-flat side of the bag, with the patch tear initiator being afirst patch tear initiator in the first patch, with the first patch tearinitiator being aligned with the first bag tear initiator, with thepatch bag further comprising and a second patch adhered to a secondlay-flat side of the bag, the second patch having a second patch tearinitiator which is aligned with the second bag tear initiator.